LevelDB vs. std::map

Question

In our application we use std::map to store (key, value) data and use serialization to store that data on disk. With this approach we are finding that the disk I/O

Answer 1

LevelDB just does something else than std::map.

Are you really saying you want (high performance) persistence for std::map?

• look at std::map with a custom allocator. Allocate the entries from a memory mapped region and use fsync to to ensure the information hits the disk at strategic moments in time.

  • mmap
  • boost iostreams memory mapped files

• perhaps combine that with EASTL (which boasts a faster std::map and thrives with custom allocators - in fact they have no default allocator)

  • EASTL

• look at tuning your hash_map (std::unorderded_map); if hash_maps are slower, you should look into (a) loadfactor (b) hash function tuning

  • docs

• last but not least: evaluate the use of Boost Serialization for binary serialization of your map (whatever implementation you picked). In my experience Boost Serialization performance is top of the bill.

  • Boost serialization